1. Lock all panels
Make sure that all panels are locked and therefore all sections are sealed along the whole closing line.
2. Flank transmission
Make sure that the structure prevents flank transmission.
3. Flat floor
Make sure that the floor is not uneven. Dents in the floor cause sound to travel under the wall’s sealing ledges.
4. Troubleshooting in the dark
Switch the lights on in one room. Close and lock the wall properly. Switch the lights off in the room you are in. Make sure that you do not see any light through the wall. Where light passes, so does sound.